1. Field of the Invention
The present invention relates to a structure for supporting a seat of a height-adjustable chair.
2. Description of the Related Art
The applicant of the present invention has proposed a height-adjustable chair (chair with a height-adjustable seat) with a foldable seat of which height can be adjusted in a stepless manner (refer to Publications of Japanese Examined Utility Model Nos. 1-8204, 4-45562, and 1-11089 and the like). As shown in FIG. 14a, a typical height-adjustable chair comprises a front leg unit 101 on the outer side of an inverted almost U shape, an auxiliary frame 102 disposed on the inside of the front leg unit 101 with a gap, rear legs 103 closably attached to either the front leg unit or the auxiliary frame, a pair of right and left brackets 104 whose rear portions are positioned in the gap between the front leg unit 101 and the auxiliary frame 102, and a seat 105 attached to the top face on the front side of each of the brackets 104. In the rear portion of each of the brackets 104, as specifically shown in FIG. 14b, a front engagement piece 106 and a rear engagement piece 107 for maintaining the angle of the bracket 104 are provided.
As shown in FIGS. 15a and 15b, the distance between the front engagement piece 106 and the rear engagement piece 107 is set to be slightly wider than the dimention in the front/rear directions (thickness or diameter) of each of the front leg unit 101 and the auxiliary frame 102. Consequently, when the bracket 104 is inclined rearward as shown in FIG. 15b, the seat 105 can be moved vertically. When the seat 105 is inclined forward as shown in FIG. 15a, the front and rear engagement pieces 106 and 107 come into contact and engagement with the opposite faces of the front leg unit 101 and the auxiliary frame 102, so that they are fixed in the position. By retaining a retaining piece (reference numeral 109 in FIG. 14b) provided between the front leg unit 101 and the auxiliary frame 102 by a slit 108 at the rear end of the bracket 104 in the state where the front side of the seat 105 is lifted and folding the rear legs 103, the chair can be folded.